Bending the Limits of Batteries

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The future of flexible smart phones and electronic newspapers that you can roll up and refresh could be closer than you think. Professor Zhang Qing and his researchers have created two flexible anodes for lithium-ion batteries that are essential to developing bendable and foldable electronics.

Their anodes – which are battery components through which electricity flows from the battery into the device and vice versa – use titanium dioxide and soft silicon. When the researchers tested the anodes in flexible batteries, the batteries could be bent repeatedly without deforming or breaking. Bent or not, they could also power a light emitting diode or LED – the building block of LED display screens on televisions and smart-phones. Past flexible anodes by other scientists had weak flexibility, low rate capabilities, which means the batteries would take a long time to charge, and short cycle lives that would have doomed products to early retirement.

One of the EEE anodes comprises carbon nanowire structures coated with titanium dioxide. While titanium dioxide is low-cost, environmentally friendly and harmless, it has poor electronic conductivity – electrons that move and create an electricity current have to plod across the material. The nanowire structure has numerous tiny cables each coated with a thin layer of titanium dioxide. The anode has a lot of titanium dioxide in total so the battery lasts longer before it becomes unusable, and it can charge quickly because the electrons travel only short distances in the thin titanium dioxide layers.

The other EEE anode has flexible plastic nanofibers coated with very electronic conductive nickel and then silicon, which can hold more charge per gram compared to traditional graphite anodes. The lightweight invention can also reduce a conventional battery’s weight by more than 20 percent.

Professor Zhang Qing from EEE said both anodes further flexible lithium-ion batteries’ development, adding: “They could be used in roll up displays, implantable medical devices and wearable devices.